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Abstract

A thin-film electroluminescent (EL) panel operating as a matrix-addressed display is provided with a light sink layer immediately behind the phosphor layer thereof to enhance the legibility of the display under high ambient light conditions. The light sink layer is formed of a p-type semiconductor compound material comprised of 20% lead telluride and 80% cadmium telluride doped with indium. The addition of the indium into the material introduces free electrons which compensate for the hole carriers therein and thereby increases the specific resistivity of the material. The addition of lead into the semiconductor compound material forms the lead telluride which in combination with the cadmium telluride reduces the energy band gap of the material to effectively absorb the ambient light in the visible range which is the source of the bad legibility. Moreover, the lead serves to reduce the mobility of the free charge carriers in the material and thereby further increases the specific resistivity of the material. Thus, the combined effects of the indium and the lead provide the semiconductor compound material with a specific resistivity in the range of 10.sup.8 to 10.sup.12 ohm-centimeter. Such a high specific resistivity material for the light sink layer is especially useful in enabling the EL panel to operate with a relatively steep luminance vs. voltage characteristic curve as required for multiplexing operation of the matrix-addressed EL panel.

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